ｿｰｽｺｰﾄﾞは以下のようになります





Sub Auto_Open()


Dim aaa As String
Dim doc As HTMLDocument
Dim coll As IHTMLElementCollection
Dim select1 As IHTMLSelectElement
Dim txtInput As IHTMLInputElement
Dim txtOutput As IHTMLInputElement
Dim btn As IHTMLInputElement

wkstname = CreateObject("WScript.Network").ComputerName
pcnamae = CreateObject("WScript.Network").UserName

tmname = ActiveWorkbook.Name
syu999 = ThisWorkbook.Name
syu888 = ActiveSheet.Name

Dim FileName_InFolder As String

'ﾌｫﾙﾀﾞのﾊﾟｽを取得
FileName_InFolder = "C:\Users\" & pcnamae & "\Downloads"

'すべてのﾌｧｲﾙ指定
FileName_InFolder = FileName_InFolder & "\*.*"

'ﾌｧｲﾙの削除
If Dir(FileName_InFolder) <> "" Then Kill FileName_InFolder


Dim ie As New InternetExplorer
ie.Navigate "http://kyodo-web/kyodo/servlet/login?WWSeihon"
ie.Visible = True


While ie.Busy = True Or ie.ReadyState < READYSTATE_COMPLETE
DoEvents
Wend

Set doc = ie.document
Set coll = doc.getElementsByTagName("BODY")
While coll.Length <= 0
DoEvents
Wend



Set select1 = doc.getElementsByName("vCMB").Item(0)
select1.selectedIndex = 17



doc.getElementById("vTANTOPASS").Value = "sato"



doc.getElementById("BUTTON1").Click



end sub

専用の Excelﾌｧｲﾙを作って､
Workbook_Open を利用してはどうでしょうか

ｾｷｭﾘﾃｨｿﾌﾄの仕業のような気がしませんか？
book開いたとたん､ﾌﾞﾗｳｻﾞに値をｾｯﾄしてｸﾘｯｸしてsendkeysするっていうのが､凄くｳｨﾙｽっぽくて怪しまれている､という感じがします｡
確実な根拠は無いですが､予想です｡